Recently, a new class of materials - called nanoglasses - with a glassy structure was synthesized. The novel feature of these materials is that the atomic structure in the entire volume of the material as well as the density of the material can be tuned. Nanoglasses are generated by introducing interfaces into metallic glasses on a nanometer scale. Interfaces in these nanoglasses delocalize upon annealing, so that the free volume associated with these interfaces spreads throughout the volume of the glass. This delocalization changes the atomic structure and the density of the glass throughout the volume. In fact, by controlling the spacing between the interfaces introduced into the glass as well as the degree of the delocalization (by modifying the annealing time and/or annealing temperature), the atomic structures as well as the density (and hence all structure/density dependent properties) of nanoglasses may be controlled. A comparable tuning of the atomic structure/density of crystalline materials is not conceivable, because defects in crystals do not delocalize upon annealing.